Joy – a midwifery student at Hertfordshire University, Hatfield – was last seen on December 26 last year.

The case is being treated as suspicious and a 40-year-old man from London was arrested on suspicion of murder and released on bail pending further enquiries.

Det Ch Supt Karena Thomas from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit said that Joy is a member of a church near Hainault Street, in Ilford, which she “described as a community that feels like her family”.

Video footage shows Joy attending a celebration at this church on Boxing Day last year, the last evening she was seen in person.

Joy Morgan. Photo: Herts Police

Classmates were also in contact with Joy through WhatsApp the following day and discussed coursework.

This was the last time she was heard from and she was reported missing on February 7.

As part of the investigation, officers are keen to trace a distinctive Honda that Joy regularly travels in.

The vehicle’s owner has been identified and spoken to but it is believed that the vehicle is linked to Joy’s disappearance.

“Joy is described as a focused and determined student,” Det Ch Supt Tomas said.

“Her disappearance is completely out of character and all avenues we have explored to establish her whereabouts so far have come back negative.

“Joy has been missing for over a month and we, along with her family, are growing increasingly concerned for her safety.

Joy is described as black, of slim build, around 5ft 5in tall, with black afro-style hair which she often covers with a scarf.

She added: “We are remaining really open minded about how and why Joy may have gone missing.

“She may have opted to take time out and if that is the case I would urge her to make contact with us on 101 or contact the Missing People charity on 116 000 to let us know she is ok.

“We just want to know that she is safe and well.

“However, we also need to consider the context in which Joy has gone missing and given the sudden nature of her disappearance and the non-contact with friends, family or with fellow worshippers at her church, at this stage, sadly, we have to consider that she may have come to harm.”

She added: “This is understandably a devastating and worrying time for Joy’s family, made even more poignant by the fact that she should have been celebrating her 21st birthday last Wednesday, February 13).

“We are supporting Joy’s family with specially trained officers throughout our enquiries.

“I am urging anyone with information about Joy’s whereabouts to get in touch by calling us on the non-emergency number 101.

“Any information you have, no matter how small it might seem, could be vital in finding out where Joy is.”